/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/


const fn = val => new Promise((resolve, reject) => {
  setTimeout(function () {
    resolve(val)
  }, 10)
})

fn('hello')
  .then(res1 => fn(res1 + 'lago'))
  .then(res2 => fn(res2 + 'I ♥ U'))
  .then(res3 => { console.log(res3) })






